The present invention relates to a ship for recovering petroleum products floating at the surface of the sea and to a mobile installation for storing and transporting these petroleum products.
Numerous methods and devices for containing and removing petroleum products floating on the surface of the sea, for example following a shipwreck or alternatively during uncontrolled discharge from an oil well on the seabed, are known.
One of these devices consists in using a flexible sheet made of a dense material which is kept afloat on the surface of the water at its upper part using floats while the remainder of the collecting device is oriented vertically in the sea, usually under the action of a counterweight placed along its lower edge.
This kind of collecting device has generally to be employed by various ships or by special ships, both in terms of erecting it and in terms of positioning it.
In use, it has become apparent that this known collecting device suffers from numerous difficulties and is not as effective as might be desired as far as containing and collecting petroleum products are concerned, particularly in the case of a sea with a great deal of swell where there are strong currents and short and changeable waves.
As a result of this, given the absence of floating stability, petroleum products may, under certain circumstances, easily escape over or under the sheet.
A certain number of special ships which recover petroleum products which have spread out in large slicks on the surface of the sea and which convey these products to storage reservoirs are also known.
In this respect, a ship which has a ramp that is inclined in its direction of travel, extending above sea level and ending below sea level, configured as a skimmer and which is continued into a collecting reservoir that acts as a settling chamber is known.
This known device is not entirely satisfactory given that its effectiveness is limited because the skimmer, particularly when the sea is rough, recovers a mixture which is essentially made up of water.
Furthermore, the variable level at which the ship sits in the water contributes to the lack of reliability of this type of device.
Recovery ships which comprise intakes connected to pumping means for transferring petroleum products floating on the surface of the sea to a storage reservoir are also known.
However, in the case of petroleum products with a high viscosity, the intakes and the pumping means soon become clogged and the apparatus no longer works.
In general, the collecting ships used have limited effectiveness and are reliant on atmospheric conditions.
In addition, they have a limited storage capacity which means that they have to return frequently to the nearest port to off-load the petroleum products recovered.
To avoid these drawbacks, it is also known practice to use an intermediate ship with a large storage capacity, such as an oil tanker, located near to the polluted zone.
However, in this case also, the transfer of petroleum products between the collecting ships and the storage ship is reliant on the atmospheric conditions and can be carried out only when the sea is calm, thus limiting the speed of intervention of the pollution-fighting means.
Now, it is known that the speed of intervention is an essential factor in preventing slicks of petroleum products from reaching the nearest shoreline.
An object of the invention is therefore to provide a ship for recovering petroleum products floating at the surface of the sea which remedies the aforementioned drawbacks and which allows these products to be collected and removed effectively out at sea.
Another object of the invention is to provide a mobile installation for storing and transporting the petroleum products recovered by such ships.
A subject of the invention is therefore a ship for recovering petroleum products floating on the surface of the sea, characterized in that it comprises:
an open front part equipped with a rotary drum which is partially submerged and comprises longitudinal elements that can be moved with respect to the external surface of this drum between a projecting position and a retracted position,
a hopper situated behind the drum for recovering the said products removed by this drum, and
means for transferring these products from the hopper to a settling and storage tank.
According to other features of the invention:
the drum comprises a cylindrical outer driven in rotation and equipped, at regular intervals, with longitudinal slots each containing one of the said elements,
each element is formed of a vane sliding in the corresponding slot and connected to means of movement between the projecting position for scooping up the petroleum products and the retracted position in the region of the hopper for tipping these products out into the said hopper,
the means of moving the sliding vanes are formed, on the one hand, of at least one stationary cam having a cylindrical portion concentric with the outer and corresponding to the projecting position of the vanes and a position curved in towards the centre of the outer and corresponding to the retracted position of the said vanes and, on the other hand, of a guide rail mounted on the edge face of the said cam and intended to collaborate with carriages each connected to the foot of a vane,
the outer of the drum is formed of circular sectors separated from one another by spacer pieces forming between the edges of two adjacent sectors the said longitudinal slot and radial passages through which the foot of the corresponding vane passes,
the drum can be moved vertically,
the drum is associated with means for scraping the external surface of the outer,
the scraping means are formed by the upper edge of the front wall of the hopper kept pressed against the external surface of the outer by at least one elastic return member,
the lower edge of the front wall of the hopper is hinged about a horizontal axle,
the hopper is equipped with a member for scraping the internal surface of the front wall so as to push the petroleum products towards the bottom of the said hopper,
the scraping member is formed of a telescopic blade hinged about a hinge pin between the upper and lower edges of the front wall of the said hopper,
the side walls of the open front part of the ship comprise intakes for the petroleum products, which intakes are connected to the said storage tank,
the recovery ship comprises at least one stabilizer plate which can be moved between a position pressed against the bottom of the hull of this ship and a position away from the said bottom.
Another subject of the invention is a mobile installation for storing and transporting petroleum products, characterized in that it comprises a logistic ship, the hull of which is equipped with at least one storage tank, with a zone for docking with at least one recovery ship as mentioned above and with means for transferring these products from the said recovery ship to the said storage tank.
According to another feature, the docking zone is formed inside the logistic ship and communicates with the sea via the stern of the said logistic ship.